Extrapelvic Endometriosis: Sciatic
While endometriosis most commonly develops on the pelvic structures including the rectovaginal septum, bladder, bowels, intestines, ovaries and fallopian tubes, it has also been found in uncommon, distant locations. The exact prevalence of extrapelvic endometriosis by site is unknown due to the small number of well-designed epidemiological studies; however, unexpected findings include (but are not limited to) the rectus abdominis muscle (“abs”), the brain and eyes, in surgical scars, the upper and lower respiratory system, diaphragm, pleura and pericardium, abdominal wall, thorax and nasal mucosa. Though exceedingly rare, intrahepatic endometriosis and disease even as far remote as the gastrocnemius have also been reported. Extrapelvic disease, though less common, can manifest in a variety of ways e.g. catamenial pneumothorax when affecting the lungs.
One consideration for some patients who may present with specific, regional symptoms is sciatic endometriosis.
Few if any laboratory tests are valuable in the endometriosis diagnostic spectrum in general, as markers e.g. CA-125 have very low specificity and sensitivity to date. Imaging tests (MRI, ultrasound, CT scan) can be more specific and helpful (particularly in the surgical planning stage), but it is very difficult if not impossible to confirm or exclude a diagnosis of endometriosis based on symptoms and tests alone. Likewise, though some may opt for a ‘diagnosis’ through application of hormonal therapy, such approach is far from accurate. True confirmation can only be obtained through surgical biopsy. Therefore, suspected extrapelvic disease should never be dismissed out of hand.
Sciatic endometriosis is not abundantly common – but it should always be included in the diagnostic approach to pain and symptoms affecting the sciatic nerve distribution. One of the first cases of biopsy-confirmed sciatic endometriosis was described by Denton & Sherill in 1955. Since then, many additional cases have appeared in the literature. Symptoms that may lead to suspicion of sciatic disease may be predominantly left-sided, though infiltration of the pelvic wall and somatic nerves causing severe neuropathic symptoms due to endometriosis infiltrating the right sciatic nerve has also been documented.
Pain may begin just before menstruation and last several days after end of flow and be accompanied by motor deficits, low back discomfort radiating to the leg, foot drop, gait disorder due to sciatic musculature weakness, cramping and/or numbness radiating down the leg, often when – but not limited to – walking, especially long distances, and tenderness of the sciatic notch. There may also be positive Lasègue’s Sign (an indication of lumbar root or sciatic nerve irritation in which ‘dorsiflexion of the ankle of an individual lying supine with the hip flexed causes pain or muscle spasm in the posterior thigh’ [Kosteljanetz et al]). There is almost always a history of pelvic endometriosis. Left untreated, sciatic endometriosis may cause nerve damage.
Physical examination may reveal various neurological deficits involving the sciatic nerve rootlets. There may be localized tenderness over the sciatic notch, but this is not always found. Pelvic examination may also even be normal. Imaging can aid in diagnosis, though ultimately a visual (surgical) diagnosis is indicated. Early diagnosis and treatment is indeed critical in order to minimize the damage. While sacral radiculopathies (pudendal, gluteal pain), vascular entrapment or sciatic neuralgia may be at the root of symptoms for some individuals, in patients with sciatica of unknown genesis and/or suspicion of pathology such as endometriosis, laparoscopic exploration of the sacral plexus and/or sciatic nerve is advisable.
Sciatic endometriosis is generally treated the same way as pelvic disease: preferably gold-standard surgical eradication (excision). When not possible, a course of medical therapy may suppress symptoms until such time as the patient can receive proper surgical intervention with a skilled, minimally invasive pelvic surgeon who has vast experience in highly complex cases of endometriosis. Physical therapy with a skilled PT specializing in endometriosis and CPP can also be very helpful.
It is very important to understand that not every patient with symptoms relating to the lumbosacral plexus or proximal sciatic nerve bundle will actually have sciatic endometriosis, as there can be several differential diagnoses. However – endometriosis can be a real (albeit less common) cause of nerve injury and symptomology. This extrapelvic manifestation of the disease must be considered in the differential diagnosis of those with symptomatic presentation, particularly if a history of endometriosis or chronic pelvic pain is present.
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© 2013 by the Center for Endometriosis Care. Last update: September 2018. In-text citation links to third party sources provided for information purposes only. Links do not indicate affiliation with or endorsement by the Center for Endometriosis Care.